Seeing in the dark: High-order visual functions under scotopic conditions

Ayelet McKyton, Deena Elul, Netta Levin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


It is unknown how and to what degree people function visually in almost complete darkness, where only rod photoreceptors are active (scotopic conditions). To explore this, we first tested scotopic acuity and crowding. We demonstrated the ∼1° foveal scotoma and found that crowding increases with eccentricity, resulting in optimal scotopic discrimination 2° into the periphery. We then investigated whether these limitations affect high-level foveal tasks. We recorded eye movements while testing reading and upright/inverted face matching under photopic and scotopic conditions. Under scotopic conditions, participants read accurately and showed a face inversion effect. Temporally, fixation durations were longer. Spatially, surprisingly, participants did not avert their gaze 2° into the periphery. Instead, they fixated on similar locations as under photopic conditions, locations that were shown to correlate with global perception. We propose that this result suggests global perception governs under scotopic conditions, and we discuss how receptive-field properties support this conclusion.

Original languageAmerican English
Article number108929
Issue number2
StatePublished - 16 Feb 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s)


  • Biological sciences
  • Cognitive neuroscience
  • Natural sciences
  • Neuroscience
  • Sensory neuroscience
  • Systems neuroscience


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